Flashing LED; also, by extension,
the name of a solar engine
based on a flashing LED. A flashing
LED is just an LED
with a built-in microcircuit to cause it to flash
periodically. Since the FLED draws current
when it flashes, we can use FLEDs to drive a number of
timing-dependent circuits (via the fact that it periodically
becomes conductive).

Like other LED, FLEDs
are light-sensitive, and so flash faster in brighter light.
Note that some FLEDs need 3 V
minimum to work in, but FLEDs don't
in general require current-limiting resistors (at least,
I've never seen one that does).